Have you looked at Beagle? Sponsored by Novell, it is a full text
indexing and retrieval system.
The official documentation is here:
http://beaglewiki.org/Main_Page
I've begun to document my real world experience with Beagle and Fedora
Core 4:
http://www.antezeta.com/beagle_fedora.html
There are still a few open issues I've indicated I want to address;
feedback is welcome.
You should also be able to install Beagle on FC 3, but I haven't done
this with the latest Beagle version.
Sean